Network switches/switching units are at the core of any communication network. A network switch typically has one or more input ports and one or more output ports, wherein data/communication packets are received at the input ports, processed by the network switch through multiple packet processing stages, and routed by the network switch to other network devices from the output ports according to control logic of the network switch.
Table search has been widely adopted for the control logic of the network switch, wherein the network switch performs search/lookup operations on the tables stored in the memory of the switch for each incoming packet and takes actions as instructed by the table search results or takes a default action in case of a table search miss. Examples of the table search performed in the network switch include but are not limited to: hashing for a Media Access Control (MAC) address look up, Longest-Prefix Matching (LPM) for Internet Protocol (IP) routing, wild card matching (WCM) for an Access Control List (ACL) and direct memory access for control data. The table search in the network switch allows management of network services by decoupling decisions about where traffic/packets are sent (i.e., the control plane of the switch) from the underlying systems that forwards the packets to the selected destination (i.e., the data plane of the switch), which is especially important for Software Defined Networks (SDN).
During its operation, the condition and/or status of the network switch may change, which may require the tables in the memory of the network switch to be updated accordingly to reflect such change. For a non-limiting example, when one of the output ports of the network switch is down, all traffic/packets currently being routed to the port need to be rerouted to another port and all relevant entries in the routing tables of the network switch need to be updated with the destination (MAC) address of the new port. For another non-limiting example, if an enterprise user would like to switch all of its machines from one virtual local area network (VLAN) to another, all routing tables for packets from these machines need to be updated to reflect such change.
Traditionally, updates to the tables in the network switch are performed by an external control unit/controller, which monitors the status of the network switch and performs updates on the tables directly. Since a table to be updated may be huge in size (e.g., having over one million entries), identifying all entries in the table that need to be updated and replacing all the identified entries with new data would consume a lot of computing resources (e.g., CPU and memory) of the control unit. In addition, when the control unit is updating the table remotely over a communication network, the instructions from the control unit to the switch to search and update the relevant entries in the table one by one would cause communication bottleneck between the control unit and the network switch.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent upon a reading of the specification and a study of the drawings.